It has been more than a century since the photoelectric effect was discovered by Einstein, and half a century since a solar cell developed by the National Aeronautics and Space Administration (NASA) of the United States was used in artificial satellites. However, power generation projects that are known to be based on the solar cell for a few decades have not yet been successful as profitable self-supporting projects. The primary reason is the high price of a photovoltaic panel. It was reported on April, 2013 that the photovoltaic panel can be supplied at a price of about $1 per watt (W). In the case of Korea, it is reported that a supply price of electric power is about $0.1/KWh. A purchase price of the photovoltaic panel required for 1 MW-class photovoltaic power generation plant and an annual electricity production capacity (electric power sale) are compared as follows (in the case of Korea, it is reported that average photovoltaic power generation can be conducted using sunlight of 1 KW/m2 for about 3.5 hours per day on average when annualized.).
Price of 1 MW-class photovoltaic panel: $1,000,000 ($1/Watt)
Annual electricity production capacity of 1 MW-class photovoltaic panel (price of annually produced electric power): 1 MW×3.5 h×365 days=1,2775 MWh/year ($127,750/year)
In detail, in view of the fact that income obtained by selling electric power for 7.8 years should be invested for only an expense required to purchase the photovoltaic panel and other incidental expenses (it is reported that, excluding a land cost, an expense about equivalent to the price of the photovoltaic panel is invested), a photovoltaic power generation industry is not very attractive at this point. It is reported that some districts, such as Italy, Hawaii, etc. in which a price of commercial electric power is highly fixed and which have an abundance of solar radiation, approach grid parity. Grid parity refers to a point in time at which the price of commercial electric power is equal to the cost of photovoltaic power generation. In the case of Korea, the supply price of electric power is relatively low, and it is more difficult to achieve the grid parity.